1. Field of the Invention
This invention relates to telephone systems and, in particular, to a method and apparatus for characterizing a telephone call by identifying the calling party, called party, or the called telephone number before the call is answered.
2. DESCRIPTION OF THE PRIOR ART
Frequently, people in a household share a single telephone. In that situation, an incoming call may be intended for only one person of the household, but until the telephone has been answered, that person has no way of knowing the "called" party. A person for whom the call is not intended might answer the telephone much to the inconvenience and discomfort of the called party.
Moreover, a called party may want to screen calls he or she answers. An answering machine allows a person to screen calls, but if the person fails to pick up the line, the answering machine indiscriminately takes messages from any caller who wants to leave a message, including unwanted callers, such as bill collectors and obscene callers.
In other situations, such as in a business, an incoming telephone line is routed to many telephones. Therefore, when an incoming call is received, the called party may not answer the telephone because he or she does not know the identity of the "called party." Thus, another office worker may answer the telephone and then have to locate the called party.
Moreover, sometimes the employer wishes to prevent certain types of calls from being made. For example, the employer may wish to restrict the employees' telephone calls to a local area code. Or perhaps the employer wants to ensure that no calls with a particular prefix (i.e., "900") are made from the business.
Accordingly, a need exists for identifying the called party, the calling party, or the telephone number called before the call is answered.